Bulletin 180 - 2008 August 18

1. CSIRO Altix upgradee
2. CSIRO Data Store - upgrade to DMF commands
3. File system flushing

Note: "CSIRO" items can apply to BoM users of cherax and burnet

1. CSIRO Altix upgrade

The changeover of cherax from the Altix 3700 to the Altix 4700 is scheduled to start at 16:00 on 20th August.

Note that any queued jobs on the 3700 at the time of cut-over will be lost and will have to be resubmitted.

Testing has shown only few differences, apart from changes to the Data Migration Facility (DMF) commands as given in the next item. The operating system is at a later service pack level.

Early users have found few problems, and codes like the UK Met Office Unified Model have been run on the Altix 4700, with almost linear scaling to 16 processors (cores).

The 4700 is still available for testing until Wednesday afternoon, under the conditions previously advised in HPCbull 179.

Another outage (hopefully the last) is scheduled for the 27th to make some cabling changes which will bring the 4700's I/O subsystem up to full speed.

History:

After the move, CSIRO ASC will be running DMF on its fifth computer, its fourth site and its eighth tape technology since 1991. The host machines have gone from 2 processors to 128, from 128 Mbyte to 512 Gbyte of memory, and from 0.67 to 854 peak Gflop/s.

The 1991 tapes had a capacity of 240 Mbyte, with a speed of 3 Mbyte/s. The latest have a capacity of 500 Gbyte and a speed of 130 Mbyte/s (with compression capability as well).

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2. CSIRO Data Store - upgrade to DMF commands

On the new Altix, we have taken the opportunity to upgrade to a new version of the Data Migration Facility.

This provides several enhancements at the system level, plus upgrades to the user commands that users can use to control DMF behaviour.

The commands are:

dmls (1)

- Lists contents of directories

dmdu (1)

- summarize DMF managed disk usage

dmfind (1)

- Searches for files in a directory hierarchy

The man pages on cherax-1 show the features of these commands. Any user-written scripts that use these commands may need to be updated. In particular, the date/time format of the dmls command has changed.

The new versions of the commands have much greater compatibility with the GNU Linux commands such as ls and find. For example, the new dmfind has the [-H] [-L] [-P] options for controlling the handling of symbolic links. Consult the man pages for more details.

As a short-term compatibility measure, you can access the old versions with "module load dmf-compat", which is available now on both Altixes.

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3. File system flushing

Flushing is carried out automatically on various $WORKDIR of *flush* file systems on HPCCC and CSIRO ASC systems.

In particular, flushing of cherax /work area is looming as usage builds up.

There has not been a flush of this area since August 2007.

Please ensure that important files are not being stored here.

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